| /* DataInputStream.java -- FilteredInputStream that implements DataInput |
| Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005 Free Software Foundation |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| package java.io; |
| |
| /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 |
| * "The Java Language Specification", ISBN 0-201-63451-1 |
| * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. |
| * Status: Believed complete and correct. |
| */ |
| |
| /** |
| * This subclass of <code>FilteredInputStream</code> implements the |
| * <code>DataInput</code> interface that provides method for reading primitive |
| * Java data types from a stream. |
| * |
| * @see DataInput |
| * |
| * @author Warren Levy (warrenl@cygnus.com) |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @date October 20, 1998. |
| */ |
| public class DataInputStream extends FilterInputStream implements DataInput |
| { |
| // Byte buffer, used to make primitive read calls more efficient. |
| byte[] buf = new byte [8]; |
| |
| /** |
| * This constructor initializes a new <code>DataInputStream</code> |
| * to read from the specified subordinate stream. |
| * |
| * @param in The subordinate <code>InputStream</code> to read from |
| */ |
| public DataInputStream (InputStream in) |
| { |
| super (in); |
| } |
| |
| /** |
| * This method reads bytes from the underlying stream into the specified |
| * byte array buffer. It will attempt to fill the buffer completely, but |
| * may return a short count if there is insufficient data remaining to be |
| * read to fill the buffer. |
| * |
| * @param b The buffer into which bytes will be read. |
| * |
| * @return The actual number of bytes read, or -1 if end of stream reached |
| * before reading any bytes. |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public final int read (byte[] b) throws IOException |
| { |
| return in.read (b, 0, b.length); |
| } |
| |
| /** |
| * This method reads bytes from the underlying stream into the specified |
| * byte array buffer. It will attempt to read <code>len</code> bytes and |
| * will start storing them at position <code>off</code> into the buffer. |
| * This method can return a short count if there is insufficient data |
| * remaining to be read to complete the desired read length. |
| * |
| * @param b The buffer into which bytes will be read. |
| * @param off The offset into the buffer to start storing bytes. |
| * @param len The requested number of bytes to read. |
| * |
| * @return The actual number of bytes read, or -1 if end of stream reached |
| * before reading any bytes. |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public final int read (byte[] b, int off, int len) throws IOException |
| { |
| return in.read (b, off, len); |
| } |
| |
| /** |
| * This method reads a Java boolean value from an input stream. It does |
| * so by reading a single byte of data. If that byte is zero, then the |
| * value returned is <code>false</code>. If the byte is non-zero, then |
| * the value returned is <code>true</code>. |
| * <p> |
| * This method can read a <code>boolean</code> written by an object |
| * implementing the <code>writeBoolean()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>boolean</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading |
| * the boolean |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeBoolean |
| */ |
| public final boolean readBoolean () throws IOException |
| { |
| return convertToBoolean (in.read ()); |
| } |
| |
| /** |
| * This method reads a Java byte value from an input stream. The value |
| * is in the range of -128 to 127. |
| * <p> |
| * This method can read a <code>byte</code> written by an object |
| * implementing the <code>writeByte()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>byte</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the byte |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeByte |
| */ |
| public final byte readByte () throws IOException |
| { |
| return convertToByte (in.read ()); |
| } |
| |
| /** |
| * This method reads a Java <code>char</code> value from an input stream. |
| * It operates by reading two bytes from the stream and converting them to |
| * a single 16-bit Java <code>char</code>. The two bytes are stored most |
| * significant byte first (i.e., "big endian") regardless of the native |
| * host byte ordering. |
| * <p> |
| * As an example, if <code>byte1</code> and <code>byte2</code> |
| * represent the first and second byte read from the stream |
| * respectively, they will be transformed to a <code>char</code> in |
| * the following manner: |
| * <p> |
| * <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code> |
| * <p> |
| * This method can read a <code>char</code> written by an object |
| * implementing the <code>writeChar()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>char</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the char |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeChar |
| */ |
| public final char readChar () throws IOException |
| { |
| readFully (buf, 0, 2); |
| return convertToChar (buf); |
| } |
| |
| /** |
| * This method reads a Java double value from an input stream. It operates |
| * by first reading a <code>long</code> value from the stream by calling the |
| * <code>readLong()</code> method in this interface, then converts |
| * that <code>long</code> to a <code>double</code> using the |
| * <code>longBitsToDouble</code> method in the class |
| * <code>java.lang.Double</code> |
| * <p> |
| * This method can read a <code>double</code> written by an object |
| * implementing the <code>writeDouble()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>double</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading |
| * the double |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeDouble |
| * @see java.lang.Double#longBitsToDouble |
| */ |
| public final double readDouble () throws IOException |
| { |
| return Double.longBitsToDouble (readLong ()); |
| } |
| |
| /** |
| * This method reads a Java float value from an input stream. It |
| * operates by first reading an <code>int</code> value from the |
| * stream by calling the <code>readInt()</code> method in this |
| * interface, then converts that <code>int</code> to a |
| * <code>float</code> using the <code>intBitsToFloat</code> method |
| * in the class <code>java.lang.Float</code> |
| * <p> |
| * This method can read a <code>float</code> written by an object |
| * implementing the <code>writeFloat()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>float</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the float |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeFloat |
| * @see java.lang.Float#intBitsToFloat |
| */ |
| public final float readFloat () throws IOException |
| { |
| return Float.intBitsToFloat (readInt ()); |
| } |
| |
| /** |
| * This method reads raw bytes into the passed array until the array is |
| * full. Note that this method blocks until the data is available and |
| * throws an exception if there is not enough data left in the stream to |
| * fill the buffer. Note also that zero length buffers are permitted. |
| * In this case, the method will return immediately without reading any |
| * bytes from the stream. |
| * |
| * @param b The buffer into which to read the data |
| * |
| * @exception EOFException If end of file is reached before filling the |
| * buffer |
| * @exception IOException If any other error occurs |
| */ |
| public final void readFully (byte[] b) throws IOException |
| { |
| readFully (b, 0, b.length); |
| } |
| |
| /** |
| * This method reads raw bytes into the passed array <code>buf</code> |
| * starting |
| * <code>offset</code> bytes into the buffer. The number of bytes read |
| * will be |
| * exactly <code>len</code>. Note that this method blocks until the data is |
| * available and throws an exception if there is not enough data left in |
| * the stream to read <code>len</code> bytes. Note also that zero length |
| * buffers are permitted. In this case, the method will return immediately |
| * without reading any bytes from the stream. |
| * |
| * @param buf The buffer into which to read the data |
| * @param offset The offset into the buffer to start storing data |
| * @param len The number of bytes to read into the buffer |
| * |
| * @exception EOFException If end of file is reached before filling the |
| * buffer |
| * @exception IOException If any other error occurs |
| */ |
| public final void readFully (byte[] buf, int offset, int len) throws IOException |
| { |
| if (len < 0) |
| throw new IndexOutOfBoundsException("Negative length: " + len); |
| |
| while (len > 0) |
| { |
| // in.read will block until some data is available. |
| int numread = in.read (buf, offset, len); |
| if (numread < 0) |
| throw new EOFException (); |
| len -= numread; |
| offset += numread; |
| } |
| } |
| |
| /** |
| * This method reads a Java <code>int</code> value from an input stream |
| * It operates by reading four bytes from the stream and converting them to |
| * a single Java <code>int</code>. The bytes are stored most |
| * significant byte first (i.e., "big endian") regardless of the native |
| * host byte ordering. |
| * <p> |
| * As an example, if <code>byte1</code> through <code>byte4</code> represent |
| * the first four bytes read from the stream, they will be |
| * transformed to an <code>int</code> in the following manner: |
| * <p> |
| * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + |
| * ((byte3 & 0xFF)<< 8) + (byte4 & 0xFF)))</code> |
| * <p> |
| * The value returned is in the range of -2147483648 to 2147483647. |
| * <p> |
| * This method can read an <code>int</code> written by an object |
| * implementing the <code>writeInt()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>int</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the int |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeInt |
| */ |
| public final int readInt () throws IOException |
| { |
| readFully (buf, 0, 4); |
| return convertToInt (buf); |
| } |
| |
| /** |
| * This method reads the next line of text data from an input |
| * stream. It operates by reading bytes and converting those bytes |
| * to <code>char</code> values by treating the byte read as the low |
| * eight bits of the <code>char</code> and using 0 as the high eight |
| * bits. Because of this, it does not support the full 16-bit |
| * Unicode character set. |
| * <p> |
| * The reading of bytes ends when either the end of file or a line |
| * terminator is encountered. The bytes read are then returned as a |
| * <code>String</code> A line terminator is a byte sequence |
| * consisting of either <code>\r</code>, <code>\n</code> or |
| * <code>\r\n</code>. These termination charaters are discarded and |
| * are not returned as part of the string. |
| * <p> |
| * This method can read data that was written by an object implementing the |
| * <code>writeLine()</code> method in <code>DataOutput</code>. |
| * |
| * @return The line read as a <code>String</code> |
| * |
| * @exception IOException If an error occurs |
| * |
| * @see DataOutput |
| * |
| * @deprecated |
| */ |
| public final String readLine() throws IOException |
| { |
| StringBuffer strb = new StringBuffer(); |
| |
| while (true) |
| { |
| int c = in.read(); |
| if (c == -1) // got an EOF |
| return strb.length() > 0 ? strb.toString() : null; |
| if (c == '\r') |
| { |
| int next_c = in.read(); |
| if (next_c != '\n' && next_c != -1) |
| { |
| if (!(in instanceof PushbackInputStream)) |
| in = new PushbackInputStream(in); |
| ((PushbackInputStream) in).unread(next_c); |
| } |
| break; |
| } |
| if (c == '\n') |
| break; |
| strb.append((char) c); |
| } |
| |
| return strb.length() > 0 ? strb.toString() : ""; |
| } |
| |
| /** |
| * This method reads a Java <code>long</code> value from an input stream |
| * It operates by reading eight bytes from the stream and converting them to |
| * a single Java <code>long</code>. The bytes are stored most |
| * significant byte first (i.e., "big endian") regardless of the native |
| * host byte ordering. |
| * <p> |
| * As an example, if <code>byte1</code> through <code>byte8</code> represent |
| * the first eight bytes read from the stream, they will be |
| * transformed to an <code>long</code> in the following manner: |
| * <p> |
| * <code>(long)(((byte1 & 0xFF) << 56) + ((byte2 & 0xFF) << 48) + |
| * ((byte3 & 0xFF) << 40) + ((byte4 & 0xFF) << 32) + |
| * ((byte5 & 0xFF) << 24) + ((byte6 & 0xFF) << 16) + |
| * ((byte7 & 0xFF) << 8) + (byte8 & 0xFF))) |
| * </code> |
| * <p> |
| * The value returned is in the range of -9223372036854775808 to |
| * 9223372036854775807. |
| * <p> |
| * This method can read an <code>long</code> written by an object |
| * implementing the <code>writeLong()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>long</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the long |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeLong |
| */ |
| public final long readLong () throws IOException |
| { |
| readFully (buf, 0, 8); |
| return convertToLong (buf); |
| } |
| |
| /** |
| * This method reads a signed 16-bit value into a Java in from the |
| * stream. It operates by reading two bytes from the stream and |
| * converting them to a single 16-bit Java <code>short</code>. The |
| * two bytes are stored most significant byte first (i.e., "big |
| * endian") regardless of the native host byte ordering. |
| * <p> |
| * As an example, if <code>byte1</code> and <code>byte2</code> |
| * represent the first and second byte read from the stream |
| * respectively, they will be transformed to a <code>short</code>. in |
| * the following manner: |
| * <p> |
| * <code>(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF))</code> |
| * <p> |
| * The value returned is in the range of -32768 to 32767. |
| * <p> |
| * This method can read a <code>short</code> written by an object |
| * implementing the <code>writeShort()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The <code>short</code> value read |
| * |
| * @exception EOFException If end of file is reached before reading the value |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeShort |
| */ |
| public final short readShort () throws IOException |
| { |
| readFully (buf, 0, 2); |
| return convertToShort (buf); |
| } |
| |
| /** |
| * This method reads 8 unsigned bits into a Java <code>int</code> |
| * value from the stream. The value returned is in the range of 0 to |
| * 255. |
| * <p> |
| * This method can read an unsigned byte written by an object |
| * implementing the <code>writeUnsignedByte()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The unsigned bytes value read as a Java <code>int</code>. |
| * |
| * @exception EOFException If end of file is reached before reading the value |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeByte |
| */ |
| public final int readUnsignedByte () throws IOException |
| { |
| return convertToUnsignedByte (in.read ()); |
| } |
| |
| /** |
| * This method reads 16 unsigned bits into a Java int value from the stream. |
| * It operates by reading two bytes from the stream and converting them to |
| * a single Java <code>int</code> The two bytes are stored most |
| * significant byte first (i.e., "big endian") regardless of the native |
| * host byte ordering. |
| * <p> |
| * As an example, if <code>byte1</code> and <code>byte2</code> |
| * represent the first and second byte read from the stream |
| * respectively, they will be transformed to an <code>int</code> in |
| * the following manner: |
| * <p> |
| * <code>(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code> |
| * <p> |
| * The value returned is in the range of 0 to 65535. |
| * <p> |
| * This method can read an unsigned short written by an object |
| * implementing the <code>writeUnsignedShort()</code> method in the |
| * <code>DataOutput</code> interface. |
| * |
| * @return The unsigned short value read as a Java <code>int</code> |
| * |
| * @exception EOFException If end of file is reached before reading the value |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeShort |
| */ |
| public final int readUnsignedShort () throws IOException |
| { |
| readFully (buf, 0, 2); |
| return convertToUnsignedShort (buf); |
| } |
| |
| /** |
| * This method reads a <code>String</code> from an input stream that |
| * is encoded in a modified UTF-8 format. This format has a leading |
| * two byte sequence that contains the remaining number of bytes to |
| * read. This two byte sequence is read using the |
| * <code>readUnsignedShort()</code> method of this interface. |
| * <p> |
| * After the number of remaining bytes have been determined, these |
| * bytes are read an transformed into <code>char</code> values. |
| * These <code>char</code> values are encoded in the stream using |
| * either a one, two, or three byte format. The particular format |
| * in use can be determined by examining the first byte read. |
| * <p> |
| * If the first byte has a high order bit of 0, then that character |
| * consists on only one byte. This character value consists of |
| * seven bits that are at positions 0 through 6 of the byte. As an |
| * example, if <code>byte1</code> is the byte read from the stream, |
| * it would be converted to a <code>char</code> like so: |
| * <p> |
| * <code>(char)byte1</code> |
| * <p> |
| * If the first byte has 110 as its high order bits, then the |
| * character consists of two bytes. The bits that make up the character |
| * value are in positions 0 through 4 of the first byte and bit positions |
| * 0 through 5 of the second byte. (The second byte should have |
| * 10 as its high order bits). These values are in most significant |
| * byte first (i.e., "big endian") order. |
| * <p> |
| * As an example, if <code>byte1</code> and <code>byte2</code> are |
| * the first two bytes read respectively, and the high order bits of |
| * them match the patterns which indicate a two byte character |
| * encoding, then they would be converted to a Java |
| * <code>char</code> like so: |
| * <p> |
| * <code>(char)(((byte1 & 0x1F) << 6) | (byte2 & 0x3F))</code> |
| * <p> |
| * If the first byte has a 1110 as its high order bits, then the |
| * character consists of three bytes. The bits that make up the character |
| * value are in positions 0 through 3 of the first byte and bit positions |
| * 0 through 5 of the other two bytes. (The second and third bytes should |
| * have 10 as their high order bits). These values are in most |
| * significant byte first (i.e., "big endian") order. |
| * <p> |
| * As an example, if <code>byte1</code> <code>byte2</code> and |
| * <code>byte3</code> are the three bytes read, and the high order |
| * bits of them match the patterns which indicate a three byte |
| * character encoding, then they would be converted to a Java |
| * <code>char</code> like so: |
| * <p> |
| * <code>(char)(((byte1 & 0x0F) << 12) | ((byte2 & 0x3F) << 6) | |
| * (byte3 & 0x3F))</code> |
| * <p> |
| * Note that all characters are encoded in the method that requires |
| * the fewest number of bytes with the exception of the character |
| * with the value of <code>\u0000</code> which is encoded as two |
| * bytes. This is a modification of the UTF standard used to |
| * prevent C language style <code>NUL</code> values from appearing |
| * in the byte stream. |
| * <p> |
| * This method can read data that was written by an object implementing the |
| * <code>writeUTF()</code> method in <code>DataOutput</code> |
| * |
| * @return The <code>String</code> read |
| * |
| * @exception EOFException If end of file is reached before reading |
| * the String |
| * @exception UTFDataFormatException If the data is not in UTF-8 format |
| * @exception IOException If any other error occurs |
| * |
| * @see DataOutput#writeUTF |
| */ |
| public final String readUTF () throws IOException |
| { |
| return readUTF (this); |
| } |
| |
| /** |
| * This method reads a String encoded in UTF-8 format from the |
| * specified <code>DataInput</code> source. |
| * |
| * @param in The <code>DataInput</code> source to read from |
| * |
| * @return The String read from the source |
| * |
| * @exception IOException If an error occurs |
| * |
| * @see DataInput#readUTF |
| */ |
| public static final String readUTF(DataInput in) throws IOException |
| { |
| final int UTFlen = in.readUnsignedShort (); |
| byte[] buf = new byte [UTFlen]; |
| |
| // This blocks until the entire string is available rather than |
| // doing partial processing on the bytes that are available and then |
| // blocking. An advantage of the latter is that Exceptions |
| // could be thrown earlier. The former is a bit cleaner. |
| in.readFully (buf, 0, UTFlen); |
| |
| return convertFromUTF (buf); |
| } |
| |
| /** |
| * This method attempts to skip and discard the specified number of bytes |
| * in the input stream. It may actually skip fewer bytes than requested. |
| * This method will not skip any bytes if passed a negative number of bytes |
| * to skip. |
| * |
| * @param n The requested number of bytes to skip. |
| * |
| * @return The requested number of bytes to skip. |
| * |
| * @exception IOException If an error occurs. |
| * @specnote The JDK docs claim that this returns the number of bytes |
| * actually skipped. The JCL claims that this method can throw an |
| * EOFException. Neither of these appear to be true in the JDK 1.3's |
| * implementation. This tries to implement the actual JDK behaviour. |
| */ |
| public final int skipBytes (int n) throws IOException |
| { |
| if (n <= 0) |
| return 0; |
| try |
| { |
| return (int) in.skip (n); |
| } |
| catch (EOFException x) |
| { |
| // do nothing. |
| } |
| return n; |
| } |
| |
| static boolean convertToBoolean (int b) throws EOFException |
| { |
| if (b < 0) |
| throw new EOFException (); |
| |
| return (b != 0); |
| } |
| |
| static byte convertToByte (int i) throws EOFException |
| { |
| if (i < 0) |
| throw new EOFException (); |
| |
| return (byte) i; |
| } |
| |
| static int convertToUnsignedByte (int i) throws EOFException |
| { |
| if (i < 0) |
| throw new EOFException (); |
| |
| return (i & 0xFF); |
| } |
| |
| static char convertToChar (byte[] buf) |
| { |
| return (char) ((buf [0] << 8) |
| | (buf [1] & 0xff)); |
| } |
| |
| static short convertToShort (byte[] buf) |
| { |
| return (short) ((buf [0] << 8) |
| | (buf [1] & 0xff)); |
| } |
| |
| static int convertToUnsignedShort (byte[] buf) |
| { |
| return (((buf [0] & 0xff) << 8) |
| | (buf [1] & 0xff)); |
| } |
| |
| static int convertToInt (byte[] buf) |
| { |
| return (((buf [0] & 0xff) << 24) |
| | ((buf [1] & 0xff) << 16) |
| | ((buf [2] & 0xff) << 8) |
| | (buf [3] & 0xff)); |
| } |
| |
| static long convertToLong (byte[] buf) |
| { |
| return (((long)(buf [0] & 0xff) << 56) | |
| ((long)(buf [1] & 0xff) << 48) | |
| ((long)(buf [2] & 0xff) << 40) | |
| ((long)(buf [3] & 0xff) << 32) | |
| ((long)(buf [4] & 0xff) << 24) | |
| ((long)(buf [5] & 0xff) << 16) | |
| ((long)(buf [6] & 0xff) << 8) | |
| ((long)(buf [7] & 0xff))); |
| } |
| |
| // FIXME: This method should be re-thought. I suspect we have multiple |
| // UTF-8 decoders floating around. We should use the standard charset |
| // converters, maybe and adding a direct call into one of the new |
| // NIO converters for a super-fast UTF8 decode. |
| static String convertFromUTF (byte[] buf) |
| throws EOFException, UTFDataFormatException |
| { |
| // Give StringBuffer an initial estimated size to avoid |
| // enlarge buffer frequently |
| StringBuffer strbuf = new StringBuffer (buf.length / 2 + 2); |
| |
| for (int i = 0; i < buf.length; ) |
| { |
| if ((buf [i] & 0x80) == 0) // bit pattern 0xxxxxxx |
| strbuf.append ((char) (buf [i++] & 0xFF)); |
| else if ((buf [i] & 0xE0) == 0xC0) // bit pattern 110xxxxx |
| { |
| if (i + 1 >= buf.length |
| || (buf [i + 1] & 0xC0) != 0x80) |
| throw new UTFDataFormatException (); |
| |
| strbuf.append((char) (((buf [i++] & 0x1F) << 6) |
| | (buf [i++] & 0x3F))); |
| } |
| else if ((buf [i] & 0xF0) == 0xE0) // bit pattern 1110xxxx |
| { |
| if (i + 2 >= buf.length |
| || (buf [i + 1] & 0xC0) != 0x80 |
| || (buf [i + 2] & 0xC0) != 0x80) |
| throw new UTFDataFormatException (); |
| |
| strbuf.append ((char) (((buf [i++] & 0x0F) << 12) |
| | ((buf [i++] & 0x3F) << 6) |
| | (buf [i++] & 0x3F))); |
| } |
| else // must be ((buf [i] & 0xF0) == 0xF0 || (buf [i] & 0xC0) == 0x80) |
| throw new UTFDataFormatException (); // bit patterns 1111xxxx or |
| // 10xxxxxx |
| } |
| |
| return strbuf.toString (); |
| } |
| } |